1. Field of the Invention
The present invention relates generally to a shoulder adjuster for use with a seat belt device for restraining and protecting seat occupants in the event of emergency such as a vehicle collision, and more particularly, to a shoulder adjuster of the seat belt for restraining the occupants on the front seats of, e.g., an automobile.
2. Description of the Prior Art
The following is one arrangement of the seat belt devices for protecting occupants on the front seats of, e.g., an automobile. A shoulder adjuster is fitted to a center pillar of the automobile. A seat belt is folded back by a shoulder anchor attached to the shoulder adjuster, whereby the seat belt can be fed out to the seat occupant.
This shoulder adjuster is constructed to make a height of the shoulder anchor variable corresponding to a seated height of the occupant and a body shape thereof. The shoulder adjuster includes a guide rail extending in the up-and-down directions and a slide member slidable along the guide rail. The shoulder anchor is attached to the slide member.
One example of the shoulder adjuster will be given (U.S. Pat. No. 4,398,749). The guide rail is formed with a multiplicity of notches at intervals in the longitudinal direction. The slide member has engaging parts with the notches and an elastic member for biasing the engaging parts in the engaging direction. Lower cut-in edge parts of the notches are substantially orthogonal to the longitudinal direction. Upper cut-in edge parts are so obliquely orthogonal to the longitudinal direction as to expand apertures of the notches.
In the shoulder adjuster of the foregoing patent having same serial number, when the slide member is biased upwards, the engaging parts move while running over the upper cut-in edge parts (inclined to the longitudinal direction) of the notches. The slide member slides upwards. When an external force acting downward from the seat belt is applied to this slide member, the engaging parts are engaged with the lower cut-in edge parts (substantially orthogonal to the longitudinal direction) of the notches. Downward sliding of the slide member is thereby hindered.
Note that the shoulder adjuster of the foregoing patent with the same serial number is provided with a member dedicated to thrust the engaging parts in a direction opposite (hereinafter referred to as a release direction) to the engaging direction. When pushing this member, the engagement of the engaging parts with the notches is released, whereby the slide member is slidable downwards.
In the conventional shoulder adjuster, there exists a metal touch between the slide member and the guide rail, resulting in large working sounds. As a thinkable contrivance, a synthetic resin lining may be effected on the slide surface between those two components. If a large load is applied in the event of emergency in the vehicle, this synthetic resin lining is damaged. This presents a problem in which the working sounds are thereafter produced from this damaged portion.
As described above, the shoulder adjuster of U.S. Pat. No. 4,398,749 requires the member for thrusting the engaging parts in the release direction. This member is disposed upwardly of the anchor fitting part. Hence, a pull-down of the slide member involves two steps of lowering the slide member in the downward direction while pushing this member. This shoulder adjuster is therefore hard to use.
The device of the foregoing patent with the same serial number presents the following drawback. The user can not recognize that the slide member is slidable downwards by pushing the dedicated member unless the user reads thoroughly the operation manual or repeatedly makes a variety of trials and errors, resulting in a difficulty to comprehend the operating method.